If you have been on the Internet before (you're there right now!) then you are likely aware of Banksy and his delightful snarkiness.
Here are two of my favorite examples of his street art:
Graffiti is where he got his start. He is also notorious for slipping pieces into galleries and museums.
More recently though, he's been getting real, live exhibitions of his very own. The attendance to which are staggering. Here's a link on his (free) exhibition in the Bristol City Museum.
A couple highlights:
I think one of the most excellent, broad-reaching things he's done so far, however, is his "couch gag" with The Simpsons. The beginning is relatively business as usual, with Banksy references (rats, crows, vandalism) sprinkled here and there.
Right around 0:37 is where it really gets interesting and amusing.
How my Art Criticism professor hesitates to include him in our list of contemporary artists this past semester, I just don't understand.